Metal-Free Benzannulation to Synthesis of 2,3-Disubstituted Naphthalenes: Reaction of 2-(Phenylethynyl)benzaldehyde and Alkynes by Brønsted Acid

Metal-free benzannulation reaction of 2-(phenylethynyl)-benzaldehyde and alkynes proceeded in the presence of Brønsted acid under microwave irradiation to give the 2,3-disubstituted naphthalenes.This research was financially supported in part by the Kansai University Subsidy for Supporting Young Scholars, 2015.2015年度関西大学若手研究者育成経

Rotation about a Covalent Bond and Pyramidalization of an Adjacent sp2 Center are a Synchronized Molecular Motion

The correlation of the rotation about the C-alpha-C' bond and the pyramidalization of the sp(2)-hybridized carbon atom C' and its three bonding partners to a flattened tetrahedron in the substructure C-beta-C alpha H-C'(=O)-OMe of substituted methyl acetates revealed that the two processes are not independent of each other but parts of a common molecular motion, as outlined in the preceding back-to-back paper. In the present study, we generalized the substructure to X-beta-C alpha H-C'(=Y)-Z with X, Y, and Z = O, N, C, and S, extending the analysis to several hundred thousand structures of the type carboxylates, carboxamides, ketones, imines, olefins, peptides, lactates, carbothioates, and phenyl derivatives, retrieved from the Cambridge Structural Database. psi/theta Scatter plots of the individual structure points and their averaging in psi/theta(av) curves result in wavelike patterns with three maxima and minima and inversion symmetry at psi = 0 degrees and +/- 180 for a 360 degrees rotation of C-beta about the C-alpha-C' bond. The pyramidalization of the sp(2)-hybridized group C alpha CiCoCo', which is part of the aromatic system, even disturbs the planarity of phenyl rings. Density functional theory calculations confirm the results of the CSD search

Chirality of the Conformation Attacks the Planarity of the sp2 Carbon Atom in a Covalent Bond

The correlation of the rotation about the bond C'-C-alpha and the pyramidalization of the sp(2) hybridized carbon atom C' and its three bonding partners to a flattened tetrahedron was investigated for the substructure C-beta-C alpha H-C'(=O)-OMe. A search in the Cambridge Structural Database (CSD) gave 15,295 structures with a substituted methyl acetate group at the end of the molecules. The scatter plot of the rotation angle psi = O=C'-C-alpha-C-beta versus the pyramidalization angle theta = O(MeO)C'C-alpha and the psi/theta(av) curve show an unusual undulating pattern with three maxima and minima for a 360 degrees rotation about the bond C'-C-alpha. There is no net chiral induction from the (M-psi)/(P-psi) conformations of the bond C'-C-alpha to the (R-theta)/(S-theta) configurations of the flattened tetrahedron because the contributions of the three maxima and minima cancel each other. The wavelike psi/theta(av) curve demonstrates that the rotation about the bond C'-C-alpha and the pyramidalization of the group C'(=O)(OMe)C-alpha are not independent processes. They are coupled with each other in one common molecular motion. The psi/theta(av) curve appears as the third harmonic of a sinusoidal fundamental frequency. DFT calculations of the propanoate anion, methyl propanoate, and methyl 2-methylpropanoate confirm the results of the CSD search

Photocatalytic Cycloaddition Reaction of Triarylphosphines with Alkynes Forming Cyclic Phosphonium Salts

Herein reported is a photocatalytic cycloaddition reaction of triarylphosphines with alkynes. Phosphonium salts of unique bicyclic structures are synthesized through a radical pathway under mild reaction conditions. The phosphonium salts are subjected to the Wittig olefination reaction to afford structurally interesting phosphine oxides

Twofold and Threefold Sinusoidal Patterns in Coupled Molecular Motions of 184,025 Structures of Phenylethane, Nitroethane, and Carboxylate Derivatives

Scatter plot analyses for 14,169 phenylethanes of the substructure C beta-C alpha H2-Ph with three open coordination positions at C beta and 150,568 phenylethanes of C beta-C alpha HX-Ph with an additional open coordination position X at C alpha have been performed, based on searches in the Cambridge Structural Database. The correlation of rotation angle psi = C beta-C alpha-Ci-Co with a pyramidalization angle theta = Co-Co '-Ci-C alpha in a 360 degrees rotation about the bond C alpha-Ci reveals a sinusoidal pattern with three maxima and minima, whereas the correlation of rotation angle psi with bond angle omega = C beta-C alpha-Ci and bond length d = C beta- C alpha results in sinusoidal patterns with two maxima and minima. A total of 3993 nitro derivatives of the substructure C beta-C alpha HX-NO2 confirm the results and show that atoms Ci/Co/Co ' in the phenyl compounds can be replaced by atoms N/O/O ' without any change in the two- and threefold patterns. In 15,295 methyl acetates of the substructure C beta-C alpha HX-C '(=O)OMe, pyramidalization of the group C alpha C '(=O)OMe results in a chiral flat tetrahedron with four different corners. (R theta)/(S theta) selectivity in the configuration of the tetrahedron is induced by the bonds C alpha-C beta, C alpha-H, and C alpha-X, emanating from the tetrahedral center C alpha. It is surprising that bonds as different as C alpha-C beta, C alpha-H, and C alpha-X (X = H, C, N, O, S, etc.) give almost the same induction intensities